With the advancement in engine designs, there is a need to provide a control device for fuel injectors such that the nozzles can be opened and closed rapidly and precisely. It is known that a sharp cut off of fluid through the nozzle and into a combustion chamber of an engine will provide for better combustion, less smoke and lower emissions. In addition, a sharp cut off of fuel into the combustion chamber can eliminate secondary injections. Up until now, most manufacturers have tried to provide a sharp cut off of fuel through the nozzle by utilizing an differential area valve which was spring biased to a closed position and was opened in response to fluid pressure impinging on the exposed surface of the valve. Two such control valves are described in U.S. Pat. Nos. 4,153,205, issued to Parrish, Jr. in 1979 and 4,269,360, issued to Hopse in 1981. Although such control valves are effective in preventing secondary injection of fuel into the combustion chamber after the valve closes, they do require an equal or a higher pressure to open than to close and this compromises the sharp cut off of fuel through the nozzle.
Now a control device and a method for operating the control device have been invented which provides for a sharp cut off of fuel through the nozzle of a fuel injector and which employs a higher pressure to close than to open.